1. Field of the Invention (Technical Field)
The invention relates to robotic structures and more particularly to an extremely light weight or low mass, seven-degree-of-freedom robotic arm capable of moving substantially throughout a hemispherical workspace.
2. Description of the Related Art Including Information Disclosed under 37 C.F.R. .sctn..sctn.1.97-1.99 (Background Art)
Computer-controlled robotic arms have been extremely used throughout the world and particularly in the United States and Japan. M. Shahinpoor, A Robot Engineering Text Book, Harper and Row Publishers, NY, USA (1987), provides a comprehensive literature survey on various kinds of prior art robot manipulators and structural designs. Two basic problems have been associated with conventional prior art robot manipulators: (1) They are generally built to be massive and stiff so as to eliminate motion control problems associated with structural flexibility; and (2) they generally move slowly because of their massive size and rigidity. Thus, there continues to be a great need in the manufacturing industry and government laboratories, as well as in defense organizations, for light weight, stiff, and subsequently fast moving robot manipulators.
The present invention, a preferred embodiment of which is shown in FIG. 1 and described herein, solves the problems caused by the deficiencies of prior art conventional robot manipulators. Since all legs of the preferred embodiment are simply supported at both ends by three-dimensional joints such as universal or ball-and-socket joints, the stresses in them are only axially distributed and thus provide stress-compensated robotic structures. The preferred embodiment of the present invention also has a minimum amount of extra mass and is essentially an ultra-light weight manipulator. The ultra-light weight, stress-compensated robotic arm is inherently capable of rapid accelerations and fast movements. It is further capable of moving symmetrically and hemispherically about its base platform; something that current robotic structures are unable to do.
The '653 application is directed in general to structures having intersecting wires. The teachings of this application are applicable to the present invention.